This invention relates to smoking articles such as cigarettes, and in particular to smoking articles having perforated wrapping material.
Popular smoking articles such as cigarettes have a substantially rod shaped structure and include a smokable material such as strands of tobacco surrounded by a wrapping material such as paper thereby forming a tobacco rod. It has been desirable to provide cigarettes having cylindrical filters positioned at one end thereof. Typically, filters are constructed from fibrous materials such as cellulose acetate and are attached to the tobacco rod using tipping material. Ventilation of the cigarette can be provided by perforating the tipping material and underlying wrapping material in order to provide air diluted delivery of mainstream smoke during use.
Methods for perforating smoking articles in order to provide for air dilution thereof involve mechanical perforation as disclosed in U.S. Pat. Nos. 4,110,448 to Stoss and 4,193,409 to Wahle et al; electrostatic perforation as disclosed in U.S. Pat. No. 4,094,324 to Bolsinger et al; or laser perforation as disclosed in U.S. Pat. Nos. 4,224,498 to Grollimund et al, 4,281,670 to Heitmann et al, 4,121,595 to Heitmann et al, and 4,249,545 to Gretz et al. A method for providing unique perforation patterns to a cigarette is proposed in U.S. Pat. No. 4,265,254 to Koch et al.
It would be highly desirable to provide a method whereby particular smoking articles or particular sets of smoking articles can be identified by the characteristic perforation pattern which is provided during manufacturing stages thereof.